Stress-resistant flexible food package



May 22, 1962 R. G. KELLER STRESS-RESISTANT FLEXIBLE FOOD PACKAGE FiledMay 3, 1960 IN VENTOR Robert G. Ke lie)" United States Patent "cc3,035,924 STRESS-RESISTANT FLEXIBLE FOOD PACKAGE Robert G. Keller,Chicago, 111., assignor to the United States of America as representedby the Secretary of the Army Filed May 3, 1960, Ser. No. 26,657 3Claims. (Cl. 99-171) (Granted under Title 35, US. Code (1952), see. 266)The invention described herein, if patented, may be manufactured andused by or for the Government for governmental purposes, without thepayment to me of any royalty thereon.

This invention relates to the production of sterile packages ofthermally processed foods, and has for its primary object to provide animproved package of the paperboard folder type which is more resistantto stress and flexing than conventional packages of this type.

In such prior conventional packages, the weakest point has been found tobe in the heat-sealed pouch which is enclosed by an outer envelope. Inthose packages, if the pouch is subjected to stress by dropping on edge,the contents distend the pouch wall, and subject the heat seal to apeeling stress which often completely disrupts the pouch with aconsequent destruction of the goods packaged therein.

It is a specific object of the present invention therefore to so locateand secure the heat-sealed pouch with in the outer container or envelopethat the circumscribing fin formed on the pouch is protected at alltimes from stresses and strains ordinarily caused by dropping thepackage.

Other objects and advantages of the invention will be apparent from thefollowing description taken in connection with the accompanyingdrawings, in which,

FIGURE 1 is an exploded perspective view of a heatsealed package aboutto be assembled;

FIGURE 2 is a perspective view of the complete package of pouch andenvelope; and

FIGURE 3 is an enlarged fragmentary sectional view taken on the line 3-3of FIGURE 2, and showing the manner of spacing the fin of theheat-sealed pouch from the walls and the edges and corners of the outerenvelope.

Referring to the drawings in greater detail and by reference numerals,the inner pouch which receives the goods to be packaged, such asthermally processed foods, is indicated generally by the numeral 1 andis comprised of two sheets 2 arranged face to face and heat sealedtogether to provide a circumscribing fin 3, thereby hermetically sealingthis portion of the package. The sheets 2 which comprise the pouch maybe formed of flexible material such as regenerated cellulose(Cellophane), metallic foil, rubber hydrochloride (Pliofilrn), etc.

The pouch as thus prepared is enclosed in flexible envelope of somewhatstiffer paperboard, cardboard, or the like and comprises a bottomportion 4, end flaps 5, and side flaps 6, one of the latter being formedwith a tongue 7 adapted to be received in a slit 8 formed in the otherside flap. The base portion 4 of the envelope is of slightly greaterarea than the area of the pouch 1, and, as shown in FIG. 3, the mainportion of the pouch is secured to the bottom portion 4 of the envelopeby adhesive 9, although it is to be understood that the pouch may beotherwise connected to the bottom portion of the envelope as by heat andpressure, or the like.

It is to be particularly noted in enlarged FIGURE 3 that the fin 3circumscribing the pouch 1 has its edge completely spaced away from theinner edge 10 of the envelope, and that it is also spaced laterally ofthe pack- Patented May 22, 1962 age from both the top and bottom of theenvelope which encloses the pouch. As hereinafter pointed out, thecritical area of a pouch of this type insofar as resistance tomechanical abuse is concerned is the area between the pouch wall and theheat seal. If the seal can be maintained in rigid condition or, atleast, held against excessive flexing, the resistance of the pouch tomechanical abuse will be considerably improved. In this connection,attention is directed to the arrows a and b of FIG- URE 3. If thepackage should be dropped, some of the force caused by the dropping willbe transferred to a shear stress between the pouch and the bottomportion of the folder, as indicated by the vertical arrows aa, of FIG.3, and the arrows 'bb, indicates how the pouch walls are restrained andthereby limit distention which would otherwise cause a peeling stress tobe applied to the heat seal. Thus, the fin 3 is protected from stressesin both directions.

From the foregoing description taken in connection with the attacheddrawings, it will be apparent to those skilled in the art that I havedevised an exceedingly simple and inexpensive modification of thesterile packages of the prior art by merely enlarging the size of theenvelope to an area slightly greater than the area of the pouchcontained therein, and that by securely attaching the main portion ofthe pouch to the bottom wall of the envelope, the heat-sealed fincircumscribing the pouch is protected from all stresses which wouldordinarily cause disruption of the seal, with a consequent destructionof the goods packaged in the container.

In accordance with the patent statutes, I have described what I nowconsider to be the preferred form of the invention, but inasmuch asvarious minor changes may be made in structural details withoutdeparting from the spirit of the invention, it is intended that all suchchanges be included within the scope of the appended claims.

I claim:

1. A stress-resistant food package comprising an inner pouch formed oftwo face-to-face flexible rectangular flat sheets of heat-scalablematerial, said sheets being heatsealed at their edges to provide acircumscribing rectangular fin and to hermetically seal the contents ofsaid package, and an outer envelope of stiffer material than saidsheets, said stiffer material having substantially the flexibilitycharacteristics of paperboard, said envelope having a rectangular bottomportion of the shape of said pouch but slightly larger in area, andflaps for enclosing said pouch; one of said pouch-forming flexiblesheets being secured to the bottom portion of said envelope along abonded surface but terminating short of said fin, so as to leave saidfin free and spaced from the inner edges of said envelope: whereby saidfin is protected by said bonding against excessive flexing and againstrupture when said package is subjected to stress.

2. A stress-resistant food package according to claim 1, wherein saidouter envelope is cardboard.

3. A stress-resistant food package according to claim 1, wherein saidheat-scalable material is metallic foil.

References Cited in the file of this patent UNITED STATES PATENTS892,074 Obici June 30, 1908 2,380,134 Waters July 10, 1945 2,457,924Salfisberg Jan. 4, 1949 2,609,301 Lindsey Sept. 2, 1952 2,658,612 NecasNov. 10, 1953 2,826,296 Mullinix Mar. 11, 1958

1. A STRESS-RESISTANT FOOD PACKAGE COMPRISING AN INNER POUCH FORMED OFTWO FACE-TO-FACE FLEXIBLE RECTANGULAR FLAT SHEETS OF HEAT-SEALABLEMATERIAL, SAID SHEETS BEING HEATSEALED AT THEIR EDGES TO PROVIDE ACIRCUMSCRIBING RECTANGULAR FIN AND TO HERMETICALLY SEAL THE CONTENTS OFSAID PACKAGE, AND AN OUTER ENVELOPE OF STIFFER MATERIAL THAN SAIDSHEETS, SAID STIFFER MATERIAL HAVING SUBSTANTIALLY THE FLEXIBILITYCHARACTERISTICS OF PAPERBOARD, SAID ENVELOPE HAVING A RECTANGULAR BOTTOMPORTION OF THE SHAPE OF SAID POUCH BUT SLIGHTLY LARGER IN AREA, ANDFLAPS FOR ENCLOSING SAID POUCH; ONE OF SAID POUCH-FORMING FLEXIBLESHEETS BEING SECURED TO THE BOTTOM PORTION OF SAID ENVELOPE ALONG ABONDED SURFACE BUT TERMINATING SHORT OF SAID FIN, SO AS TO LEAVE SAIDFIN FREE AND SPACED FROM THE INNER EDGES OF SAID ENVELOPE: WHEREBY SAIDFIN IS PROTECTED BY SAID BONDING AGAINST EXCESSIVE FLEXING AND AGAINSTRUPTURE WHEN SAID PACKAGE IS SUBJECTED TO STRESS.